A known cigarette manufacturing technique, such as disclosed in U.S. Pat. No. 4,771,794, involves the use of a suction belt which takes tobacco from a hopper and forms a rod of tobacco that is fed into the garniture area of a cigarette manufacturing machine where the tobacco rod is wrapped in paper. The rod of tobacco that is formed in the suction belt area is not generally of a consistent enough weight or density to be used directly as a high quality cigarette. Accordingly, the tobacco rod is trimmed by an ecreteur to remove excess weight or density.
The removal processing is performed by a set of trimming disks. The trimming disks comprise two coplanar, rotating, disks adjacent to one another. The trimming disks shear off excess weight or density from a tobacco rod passing over or between them by the use of a paddle wheel or brush that rotates under the disks. The disks and brush may be moved up and down to remove more or less tobacco as required.
Cigarettes often have increased density of tobacco packing at either end of the cigarette to help prevent loose tobacco from falling out of the cigarette. Known trimming disks accommodate this by having pockets in the trimming disks that allow more tobacco to pass through the disk at either end of the tobacco rod and into the garniture area of the machine. In particular, the rotation of the two trimming disks is synchronised, so that the pockets form a symmetrical profile with respect to the cylindrical axis of the cigarette. Such an approach enables a dense end of tobacco to be formed at the open ends of the cigarette. The use of such dense ends has proved very effective for retaining tobacco within a cigarette.
In contrast, the remaining central portion (body) of cigarettes has generally been provided with a constant tobacco density, and the trimming disks for the manufacture of such cigarettes have been shaped accordingly.